Originally Posted by
Barrett
Sir: My thoughts? I would start with the below.
1-Intermittent "misfire" in conjunction with simultaneous momentary CEL is always a sign that your ECM just saw something it didn't like. This is always either a 12V power interruption...or ground interruption. Check all grounds including rear sub-frame to main-frame connections closely for corrosion and loose connections. Check ECM ground closely as well.
2-Check and clean and tighten all 4 battery cable connections and battery terminals. A problem on 1 or more of them will cause your precise problem.
3-random FC's 13&21 almost always a result of faulty ground. See #1 above.
4-The CPS plug on your year XB is behind the plastic front pulley cover. Remove same, separate all connectors, clean, inspect, reconnect.
5-Remove Key Switch relay and check for corrosion...loose or broken fusebox terminals...clean...reinstall.
6-A sudden loss of power and lackluster throttle response "at speed" is almost always associated with an Interactive Exhaust Valve System failing actuator assembly and/or cable/muffler valve failing.